compiler/glsl: explicitly delete copy constructor and copy-assignment operator
What does this MR do and why?
compiler/glsl: explicitly delete copy constructor and copy-assign
Most of our visitors have custom destructors because they wrap C types,
and need to manually call destructors for those types. Because of this,
the implicitly generated copy constructors and copy-assignment operators
are not safe due copying pointers rather than data. Since we don't need
these features just delete them, so any attempt to use them would be a
compilation error. This doesn't fix any existing except stopping
coverity from complaining, but it does prevent new issues in the future.